Besides of NO_x, CO₂ is always abundantly present in the exhaust gas stream, which is important for the investigation of de-NO_x. The presence of CO₂ has an inhibiting effect on the NH₃-SCR activity at temperatures below 300°C for the Fe_0.4Ce_0.6O_2-δ catalysts. To make clear this impact of CO₂ for NH₃-SCR reaction, we further investigate the changes of NH₃ and NO_x adsorption behaviors, using in situ TPD and in situ DRIFTS technologies. The DRIFT spectra of CO₂ adsorption show that weakly adsorbed carbonate and bicarbonate species were formed, leading to the changes in adsorption and activation behaviors of NH₃ and NO_x. On the one hand, the formed carbonate and bicarbonate can act as new acid sites thereby improvement of NH₃ adsorption. On the other hand, the adsorption of NO_x on Fe-O-Ce is suppressed by CO₂ results from its competitive adsorption. Especially, the formation path of monodentate nitrate may be blocked by CO₂, which is usually active intermediate species for the NH₃-SCR reaction, resulting in the deactivation of CO₂.

除了NO _x之外，废气流中始终富含CO ₂，这对于研究de-NO _x至关重要。对于Fe _0.4 Ce _0.6 O2 _-δ催化剂，在低于300°C的温度下，CO ₂的存在对NH ₃ -SCR活性具有抑制作用。为了弄清楚CO ₂对NH ₃ -SCR反应的影响，我们使用原位TPD和原位DRIFTS技术进一步研究了NH ₃和NO _x吸附行为的变化。CO ₂的DRIFT光谱吸附表明形成了弱吸附的碳酸盐和碳酸氢盐物质，导致NH ₃和NO _x的吸附和活化行为发生了变化。一方面，形成的碳酸盐和碳酸氢盐可以充当新的酸位，从而改善了NH _3的吸附。另一方面，由于竞争性吸附而产生的CO ₂抑制了NO _x在Fe-O-Ce上的吸附。特别地，单齿硝酸盐的形成路径可能被CO ₂阻塞，而CO ₂通常是NH ₃ -SCR反应的活性中间物种，导致CO ₂失活。